Switching device



Nav. 29, 1927. 1,650,601

J. BRUYNES SWITCHING DEVICE Filed May 12, 1924 Inventor 1 Johannes Bruynes,

His AttorneyaoHANNEs BRuYnEs, or nmnnovmv, NETHERLANDS, nsslenon' 'ro' GENERAL Enid. TRIO COMPANY, A CORPORATION on NEW YonK.

swrrcnine nnvrcn.

Application filed May 12,1924, Serial no. 712,721, and in the Netherlands May 28,1923.

My invention relates to switching devices. More in particular it relates to a switching device adapted for use, for example, with a device having a positive resistance characteristic such as a tungsten lamp. Furthermore, with my invention a bimetallic interrupter may be eiiectively used withan electric lamp circuit to interrupt said circuit at regular intervals.

Theinventionis based on the observation that the high current which flows when the circuit is initially closed through a tungsten lamp has a detrimental effect. By reason of the momentary rush of high current when the circuit is initially closed (which is several times the value of the current after tacts of the interrupter become welded together.

According to the invention, means are provided .such that the total resistance in the circuit of the interrupter and the lamp varies in such a manner after the circuit is closed that the current when the circuit is initially closed is not materially higher than the current shortly thereafter, that is, than the normal operating current.

It will be understood that by the expression not materially higher is meant not sufiiciently higher to bring about the weld ing of the contacts. In the preferred arrangement the initial current flow and the normal operating current are made as near equal as possible. It is also possible to so arrange the elements that the initial current may be less than the normal operating current. However, good results are obtained when the initial current has a. value of, for example, three times that of the operating current. 7

.Whenv a lamp with a tungsten filament is used a resistance may be connected,for.example, in series with the lamp and the interrupter, which, after the lamp has been switched on, remains unvaried or decreases so that the increase of resistance of the filament is partly compensated for and becomes of less influence.

According to the invention, a resistance may also be connected in parallel with the interrupter, such that during the period that the contactsare open a current flow is main-. tained through the filament but of such small magnitude that theflfilament barely glows or does not glow at all. The temperature of the filament nevertheless is maintained at 'such adegree that the current at the-moment of closure of the contact is not materially higher than the operating cur-f rent. 'lVith this arrangement, the filament may be mounted in one lamp with the res stance connected in parallel to the inter-- rupter.

According to the invention, the inter-. rupter is preferably connected in series with a carbon filament lamp. 'As the resistance of'the carbon filament decreases as the temperature increases the object of the invention is thus attained in a'very simple and entirely satisfactory manner. A very practical embodiment 'of the invention is obtained by mounting an interrupter in the cap of'a carbon filament lamp and connecting it in series therewith.

It is essential on the one hand that the contacts of the interrupter should not adhere together and on the other hand it is desirable to provide for easily regulating the lengths of the period during which the circuitis open and during'which the circuitis closed,

According to the invention, this is possible by disposing the contact opposite the bimetallic strip on a resilient member, and by determining the extreme position of said member adjacent the bimetallic strip by or wlthinan envelope filled with a neutral gas. It is, of course, obvious that the in- .vention'is not limited to the use of contacts thus enclosed. In fact, the contacts may be used in the open air;

.Fig. 2 represents diagrammatically a deviceaccording to the invention'which comprises an interrupter and a resistance connected in parallel with the interrupter.

The interrupter shown in the drawing, Fig. 1, comprises a glass vessel 1 with a stem 2 in which the leading-in wires are sealed. The glass vessel may be partly or wholly exhausted or it may be-filled with a neutral gas such, for example,-as nitrogen or argon at a suitable pressure.

The conductor 3 serves for feeding the current to the heating wire 5 which is wound on a bimetallic strip 6 but insulated therefrom in some suitable manner, as for example by mica plates. The wire 5 ends in contact 9. The conductor 4 feeds current to a support 8. The support 8 itself is preferably non-resilient and by bending the hook 11 more or less the contact 10 may be easily adjusted. It is thus possible to regulate the period of switching on and disconnecting the lamp.

The bimetallic strip on growing hot bends upwards until the contact 10 has reached its extreme position, whereupon the current is interrupted. The strip 6 first bends slightly further but cools and-returns, the contact with the spring 7 being thus restored so that the current flows agai The interrupter may be mounted in any suitable manner in a lamp socket. The tungsten lamp with the current limiting resistance, or a carbon filament lamp alone, may be connected in series with the interrupter. It is also possible to mount the interrupter in the lamp cap.

The device shown in Fig. 2 has a filament 15 consisting for example of tungsten and connected in series with an interrupter provided with a bimetallic strip 18, which has a contact 19 that periodically contacts with a spring 17.

The filament and the interrupter are connected to a network of some suitable alternating or direct voltage V. A resistance 16 is connected in parallel to the interrupter.

The operation of the device is as follows:

Durin the heating period of the interrupter, t 1e resistance 16 is shortcircuited and the full current flows through the filament 15 which consequently becomes incandescent. By reason of the bimetallic strip growing hot the circuit is interrupted, the resistance 16 and the filament 15 being thus connected in series to the voltage V. The current is then lower than the operation current and has such a value that although the filament 15 gives out light no longer, it yet remains at a rather high temperature, so that when the interrupter closes the circuit a ain, the switching-on current is not material y higher than the operating current.

It is, of course, obvious that the relation between the initial current and the operating current can be fixed by regulating the value of the resistance 16, as the said value determines the temperature of the filament at the end of the opening period.

Good results can be obtained if the value of the resistance 16 is, for example,'equal to three times that of the resistance of the filament 15 in a cold state.

The resistance 16 may have the form, for example, of a tungsten filament and in that case the filament and the resistance may be mounted together in one lamp.

It will be understood that I do not wish to be limited to the specific construction of my invention shown and described inasmuch as variations thereof will readily suggest themselves to those skilled in the art without departing from the spirit of my invention or from the scope of the claim herein.

What I claim as new and desire to secure by Letters Patent of the United States is In an electric device, the combination of a lamp filament having a positive temperature-resistance characteristic, a resistance element with a negative temperature-resistance characteristic, a thermostatic switch having contacts for periodically short-circuiting the resistance element, an electric heater for the thermostat connected in series with one of said elements whereby when the device is connected to a source of current the filament may be made to flash on and oil, said elements being connected in series with respect to the current source whereby a harmful surge of current through said contacts during the operation of the thermostat 1s prevented.

In witness whereof, I have hereunto set my hand this twenty-second day of April,

J OHANN ES BRUYNES. 

